In the field of automatic bag filling with materials or goods in granular or powder form, the use of apparatuses for the automatic insertion of bags is becoming more and more widespread. In such an apparatus a valved bag is picked up from a pack and is then handled by devices adapted to open the valve and insert it on the nozzle of the bag filling machine, which is an operation that was carried out manually until recent times. The valved bags used may be made of paper or plastic material.
In order to pick up single bags the bag inserting apparatus is generally provided with suction cup devices which are applied on a pack of bags, adhere to the uppermost bag because of the vacuum generated in the suction cups and transfer it, one at a time, to the other devices of the apparatus which open the bag valve and insert it on the nozzle of the bag filling machine by means of several devices. Valved bags and automatic bag inserting apparatus are disclosed in U.S. Pat. No. 4,141,392 to Moltrasio, to which reference may be had for a detailed description.
Such a process of picking up bags is wholly efficient if the stacked bags are only laying on one another. However it happens more and more frequently that bags are often glued to one another, because the bags are in turn manufactured automatically and are stacked when the glue joining the various parts (generally the bottom part and the top part provided with the valve) is not completely dried. Consequently, when the first bag of the pack is picked up, it drags the underlying bag and sometimes more than one bag. In such case either two or more bags are delivered together to the bag inserting apparatus, causing it to jam and requiring intervention of the operator, resulting in clear waste of time and loss of production. When several bags are stuck together, the suction cups are not able to raise them and there is a need for a manual intervention and breakdown of the operative cycle.
It has to be noted that in some bag inserting apparatus the pick-up rate is over 2,000 bags per hour, so that the above mentioned manual interventions affect severely the output. There is consequently the problem of separating the bags stuck together before they are delivered to the apparatus and therefore the need that the feeding device of the bag inserting apparatus is not limited to the mere pick up of the bag, but is also able to separate the bags which are stuck together, so as to always deliver single bags to the bag inserting apparatus.